Ignition system



3 Sheets-Sheet 3 Oct. 1,1963 J. c. HOIBY ETAL IGNITION svsma Filed Dec.14, 1961 United States Patent 3,105,481 EGNITION SYSTEM James Hoiby andHarry E. .lorgenson, Minneapolis,

Minn, assignors to Gnan, Division of Studebaker- Pacitard (Iorporation,Minneapolis, Minn, a corporation of Minnesota Filed Dec. 14, 1961, Ser.No. 159,223 (Iiaims. (Cl. 123-179) The present invention relates tomagnetos and more particularly to an improved flywheel magneto adaptedfor use with an internal combustion engine.

In flywheel magnetos of the type in present use, there is ordinarilyincluded a stationary core structure carrying a generating coil and apermanent magnet which is carried by and rotates with the flywheel.These component parts cooperate during rotation of the flywheel toinduce a magnetic flux within the core structure and the coils.

During either hand cranking or electrical starting of an engine with amagneto of this type, there is a danger of kickback if the spark occurstoo far in advance to top dead center because spark actuation is fixed.The selection of this angle in many prior engines is a compromisebetween the angle of advance required to obtain maximum power duringnormal running and the angle of spark retardation required for startingthe engine without the danger of kickback. As a result of thiscompromise, an engine using a conventional flywheel magneto is likely tokickback if not started with a strong pull or cranking motion.

In an attempt to overcome this problem, a number of spark advancingsystems have been proposed for providing a first current pulse to thespark plug during normal running of the engine and a second or retardedpulse to be used during starting. One example of this type of ignitionsystem is illustrated by the patent to Glenday et al., U.S. Patent No.2,982,805. In the Glenday device there are provided two reversals offlux during each rotation of the crankshaft and a means is provided foractivating the breaker points of the magneto during either the first orthe second reversal depending upon whether advanced or retarded sparktiming is de sired.

In contrast to the Glenday system, the present invention utilize-s anin-rush and a reversal flux rather than two flux reversals during eachrevolution.

Briefly, according to the present invention, an in-rush of magneticenergy into the magneto core causes the current in the coil of themagneto to change from zero to a plus or minus maximum and during theflux reversal, current in the coil changes from a maximum through zeroto a maximum thereby providing double the potential diflerence found ina transition from zero to a plus or minus. Since the current in the coilwindings is dependent upon the time rate of change of the flux, themaximum flux change during in-rush is dependent upon the velocity of theflywheel. As a result, at low engine speeds the current resulting fromin-rush flux is below the amount desired for normal running. 'Duringflux reversal on the other hand, the relatively large flux change causesa much larger current which is sufficient to operate the engine at lowengine speeds. By means of this system, it is possible to use a bipolarmagnet rather than a three pole or other more complicated magneticstructure to produce the current required at low engine speeds.Moreover, the current resulting from the in-rush of magnetic flux willincrease substantially at higher speeds and will therefore provide astrong spark at normal engine running speeds. The present invention alsoprovides an improved speed responsive SJQSASE Patented Qct. 1, i963means for advancing the spark timing above a predetermined rotationalvelocity.

It is one object of the present invention to provide an improvedflywheel magneto of the type described wherein a simplified magneticstructure can be used to provide a first and second current peak, onepeak being used for normal operation and the other being used forstarting the engine.

It is another object of this invention to provide an. improved flywheelmagneto of the type described wherein a current resulting from thein-rush of magnetic flux can be used for normal opera-ting speeds and acurrent resulting from reversal of magnetic flux can be used forstarting the engine.

It is another object of this invention to provide an improved flywheelmagneto which produces a first current peak for running and a retardedcurrent peak of a greater amplitude for starting the engine wherein thefirst current peak increases in magnitude at high engine speeds.

It is still another object of this invention to provide an improvedflywheel magneto of the type described having a simplified means foroperating the breaker points at one angle relative to top dead centerfor starting the engine and at a diflerent angle for running the engine.

It is yet another object of this invention to provide 7 an improvedflywheel magneto of the type described which is compact, reliable inoperation and rugged in construction.

it is yet another object of this invention to provide an improvedflywheel magneto of the type described wherein a simplified speedresponsive means is provided for advancing breaker point operationrelative to top dead center of the engine and simultaneouslyinterrupting the operation of an engine starting motor.

These and other more detailed and specific objects will be disclosed inthe course of the following specification, reference being had to theaccompanying drawings, in which- FIG. 1 is a side elevational viewpartly in section of an internal combustion engine incorporating thepresent invention.

FIG. 2 is a vertical sectional view taken on line 2--2 of FIG. 1.

FIG. 3 is a schematic electrical circuit diagram of the magnetoaccording to the present invention.

FIG. 4 is a vertical sectional view taken on line 4-4 of FIG. 2.

FIG. 5 is an enlarged view of the timing gear and associated elementspartly broken away.

FIG. 5A is an enlarged view of a portion of FIGS. 4 and 5.

FIG. 6 is a vertical sectional view taken on line 6-6 of FIG. 4.

FIG. 7 is a graph showing the magnetic flux and primary current plottedagainst time at two different engine speeds.

FIG. 8 is a wiring diagram of the engine starter motor circuit.

FIG. 9 is a sketch showing the general features of the magnetic circuitarrangement of FIG. 2.

FIG. 10 is a vertical sectional view taken along the section line 10-10of FIG. 9.

Referring now particularly to FIGS. 1 and 2, there is shown a flywheelmagneto according to the present invention embodied in an internalcombustion engine 10'. The engine It} includes the usual engine block12, cylinders 14 and 16, pistons 18 and 20 and crankshaft 22. Thecylinders 14 and 16 are each provided with a spark plug 24, only one ofwhich is shown in FIG. 1. Connected rigidly to the crankshaft 22 bymeans of bolts 26 is a flywheel 28 A field of circumferentially spacedapart permanent magnets 30 and 32 is positioned on the inward surface ofthe flywheel. At the inward end of each of the magnets 311 and 32 areprovided a pair of pole pieces 34 and 36. The

structure comprising a pair inwardly facingsurfaces are curved to coactwith a sta- Permanent magnet 32 is provided with a magnetic north poleat its inward end and a magnetic south pole at its outward end. Thepermanent magnet 30 is provided with a magnetic south pole at its inwardend and a magnetic north pole at'its outward end. The flywheel 28 shouldeither be formed from a magnetic material or in the alternative,provided with a magnetic material at 46 between the inward ends of themagnets 311 and 32 to act as a means for completing the magnetic fluxcircuit between them. As can be seen in FIG. 2, the directhrough whichprojects one end of the crankshaft 22.

Rigidly connected to the casing 511 is .a field structure comprising anignition coil 54 and a core 56. The core 56 is made up oflaminations of'a magnetic material and has three circumferentially spaced apart legs58, 611 and 62. The outward ends of these legs are spaced very close tothe inward ends of thelpole pieces 34 and 36,

' so that magnetic energy can be transferred from the permanent magnetsto the core. The legs of the core are integrallyunited at their innerends and extend more or less radially with the outerendscircumferentially spaced apart and curved to coperate successively withthe 'curved polar faces of the pole pieces 34 and 36. A

sketch of the polestructure '56, showing the relative position of theabove described apparatus may be seen in FIGS. 9 and 7 The coil 54includes a primary coil 64 and a secondary.

coil 66 as shown in FIG. 3. The primary coil 64 is connected by means ofconductors 68 and 7G in series with a set of breaker points 80 as bestseen in FIGS. 3 and 6. A condenser 82 is connected across the breakerpoints 311 and the terminals of the, secondary coil 66 are connected bymeans of conductors 84 and 86 to the respective spark plugs 24. a V

Mounted rigidly upon the crankshaft 2 2 is a gear W best seen in FIG.l.' Mountedrotatably upon the block 12 is a second gear 92 in drivingengagement with the gear SW. The gear 12 is also in driving engagementwith one end within a suitable opening 98 in thegear cover' 511 and atthe other end within a suitable opening 1011 in support ;member 1112.The pin 96 is provided with an axial bore 97 at one end in which ismounted a plunger 99. Plunger 99 is urged outwardly bymeans of a spring101. The end of the plunger 99' abuts against the end wall of the recess1% thus'yieldably biasing the pin 96 toward the right as viewedin FIG.4.

The support member 102 can be secured to the block 12 and gear coverfit)by means of bolts 104 and 106. Gaskets 1118 are preferably providedbetween the block,

- j 12, cover 51) and members 1112, to provide aleak proof seal aroundthe compartment 110 between member 102 and cover '50. The compartment116 is preferably filled at least partially with oil.

' .posite sides ofthe' gear 94 are a pair of weights 114 and 116. Theoutward movement of the free ends of the weights 114'and 116 can belimited by means of a tact assembly 1611 to energize the starting motor.

. 4 stop pin'118 extending through the gear 94. At the inward end ofeach of the weights 114 and 116 is provided a gear sector 1211. The gearsectors 1211 are in driving engagement with gear teeth 122 provided onat least a portion of a cylindrical cam member 124 which is rotatablymounted upon the pin 96.

The cam member 124 is yieldably biased toward the gear 94 by means of ahelical coil spring 126 connected between the pin 96 and the cam 124.

The free ends of the weights 114 and 116 are urged inwardly by means ofspring 1311 connected between the gear 94 and the weights as can be bestseen in FIG. 5.

When the gear 94 is running at high speed, the free end of the weights114 and 116 will be thrown outwardly or to the right in the figure.Through the action of gear teeth 1211 and 122, the cam member 124 willtherefore be rotated in a clockwise direction relative to the gear 94 asviewed in the figure;

As can be seen in FIGS. 4, 5 and 5A, the gear 94 is substantiallyprovided with a V-sh-aped depression 132 in one face adjacent theopening therein through which the pin 96 extends. The sides of thisdepression comprise inclined-ramp surfaces. 132 is asubstantiallyV-shaped lobe 134 which extends outwardly or to the right in FIG. 4 fromthe right end of cam 124. The lobe 134 is so positioned with respect topin 96, as viewed in FIG. 4. Lobe 134 slides into the depression 132, sothat the end of lobe 134 is in contact with the left end of gear 94. g

Referring to FIGS. 4 and 8, a pair of contacts 1511 and .148 connectedto conductors 144 and 142 respectively are shown mounted on aninsulating member 1411. The movable contact.148 is mounted on aresilient electrically conductive member 146 and is held in a normallyopen position by means of a pin 152'which extends through the wall ofplate 102 and is in engagement with the end of cam 124 and so as to bepositioned axially with respect to the position of cam 124 as describedabove. When cam 124 is in its extreme lefta'hand position, the cont-actsare maintained in an open position and when cam 124 is normally opencontacts ldtl'and 148 to close. A

schematic diagram of a conventional starting motor control arrangementis shown in FIG. 8. A starting motor 147, suitably mounted in operativerelationship on the stationary engine (not shown), is adapted to beenergized from a battery 149'through conductor 142 and normally opencontact assembly drivingly connected to relay winding 145. Relay windingis connected to the negative terminal of battery 149 through conduct-or161 and to the positive terminal of battery 149through the conductor162, a parallel'path comprised of norm-ally open manually operableswitch means163 and normally open holding contact switch means 164operatively connected to relay win-ding 165, normally closed de-energizing switch means 166 operatively connected to relay winding 167,conductor 168 and conductor 142. Itrnay be seen that closing of switch163 through manual or other means serves to energize relay winding 145which is held in by the closing of relay contact assembly 164 whichestablishes a holding circuit for relay winding 145. The energiz-ationof relay winding 145 serves to close normally open con- Normally opencontacts 148 and 1541 are connected to battery 149 through conductor 142and through conductor 144, relaywinding 167 and conductor 161.

ment' of cam 124 to its right-hand'position, relay winding 167' isenergized to open its associated normally closed Cooperating with thedepression,

When normally, open contacts 148 and 1511 are closed by-the. moveof theweights 114 and 116 serves two functions.

contact assembly 166 which deenergizes relay winding 145 to de-energizethe starting motor. Once relay winding 165 has been de-energized by theopening of contact assembly 166, the starter will not again be energizedunless normally open contact assembly 163 is closed to complete acircuit to relay winding 145. The circuit shown in the schematic diagramof FIG. 8 is only an illustrative example as it will be apparent tothose skilled in the art that normally open contacts 148 and 150 may beutilized 'with a variety of starter motor control circuits andapparatus.

It will be thus understood that the outward movement The first is therotation of the timing cam 124 with respect to the gear 94 to change thetiming of breaker point operation as described hereinbelow and thesecond is the interruption of the starter motor as a result of the axialmovement of the cam 124 on the pin 96.

As can be best seen in FIG. 6, the support member 102 is provided with abore 160 in which there is slidably mounted a plunger 162. The plunger162 extends radially outward from the cam 124 through a rubber diaphragm164 which serves to seal the chamber in which the cam is contained. Thefree end of the plunger 162 is operatively associated with a breakermember 166 which is pivot-ally mounted on member 102 by means of pin168. The member 166 includes a radially extending portion 170 upon whichone of the breaker points as is positioned. Thus when the lobe of thecam 124 moves the plunger outwardly or to the right, as viewed in FIG.6, the memher 166 will pivot in the clockwise direction thereby openingthe breaker points 80 and allowing a pulse of current to be transmittedto one of the spark plugs 24. The points 80 are urged together andnormally held in a closed position by means of a resilient spring 172.The operation of the magneto will now be described. As mentioned brieflyabove, because of the compromise in ignition timing for running andstarting in a conventional engine, the engine is likely to kick back ifnot started with a firm pull or cranking motion. This problem isovercome with the present invention through the action of the speedresponsive breaker point actuation, field and magnetic structuresdescribed above. Moreover the magneto described provides substantiallyuniform ignition cur. rents for both starting and running as contrastedwith a conventional flywheel magneto which, in many cases, exhibitsstarting voltages of from one half to two thirds that of running voltagein the speed range of 100 to 300 rpm.

During operation, the permanent magnet pole group consisting of thepermanent magnets 34 and 32 in passing over the three leg laminated core56 produces two major peaks of current in the primary coil 64. First ofthese peaks in point of time is designated A and the second peak isdesignated B. As can be seen in FIG. 7, the flux in coil 54 changes fromzero to a first maximum value to create the relatively small peak Aandfrom the first maximum through Zero to a second maximum value tocreate the second and correspondingly larger peak value B. Since thevoltage output of ignition coil is directly proportional to the currentinterrupted in the primary, at rotational speeds of from about 100 to300 rpm, for example, the maximum value of the current at B will begreater than that at A. The peak designated A results from a flux changedue to the in-rush of flux as the magnetic group consisting of themagnets 30 and 32 aligns itself with the first two legs of the core andthe second peak B is due to the very rapid reversal of flux through themiddle leg of the core as the magnet group consisting of magnets 30 and32 progresses so that each of the respective magnets is aligned with thelast two legs of the core. As can be seen by comparing the two graphs ofFIG. 7, as rotational speed is increased to an operating range of from180*!) to 3600 rpm. for example, the amplitude of current peak at A willincrease and approach that of peak B, while the maximum current at peakB changes little from the starting speed to the operating speed. Whenstarting the engine, the cam 124 is set to interrupt the current at peakB thereby providing a retarded spark timing as well as more thanadequate ignition voltage during engine starting. When the speed of theengine is increased above a predetermined point, the breaker point cam124 is rotated by the action of the weights 1:14 and 116 therebyadvancing the opening of the breaker points to coincide in time with theoccurrence of peak A. The current peak at A will thus furnish therunning ignition voltage.

The angular displacement between the peaks A and B is, of course,determined by the degree of angular separation between the magnets 30and 32. We have found that very good results could be obtained byproviding an angular separation of 30 between the center lines of themagnets 39 and 32.

It is understood that suitable modifications may be made in thestructure as disclosed, provided such modifications come within thespirit and scope of the appended claims. Having now therefore fullyillustrated and described our invention, what we claim to be new anddesire to protect by Letters Patent is:

1. An ignition system for an internal combustion engine comprising incombination; an engine including a rotatable crankshaft, a sparkingmember mounted within a combustion chamber of said engine, a source ofmagnetic energy mounted for rotation upon said crankshaft, electriccurrent generating means stationarily mounted on said engine and inmagnetic energy transferring relationship with said source of magneticenergy, said generating means including a pair of output terminals, afirst switch means connected to said output terminals, actuator meansresponsive to the velocity of rotation of said crankshaft for operatingsaid first switch means at relatively high rotational speeds upon anin-rush of magnetic energy to said generating means and for operatingsaid first switch means at relatively low rotational speeds upon thereversal of the direction of magnetic energy transferred to saidgenerating means, conductor means interconnecting at least one of saidoutput terminals and said sparking member, a starter motor connected tosaid engine, circuit means interconnecting said starter motor and asource of energy therefor, said circuit means including means operableto energize said starter motor and means connected to said actuatormeans operable to dc-energize said starter motor at relatively highrotational speeds.

2. In an internal combustion engine including a rotatable crankshaft, asparking member mounted in a combustion chamber of said engine, a sourceof magnetic energy and an electric current generating means having acoil, said coil having a pair of output terminals, said electric currentgenerating means and said source of magnetic energy being mounted forrelative rotation in correspondence with the rotation of said crankshaftand means interconnecting at least one of said output terminals and saidsparking member, the combination comprising, a timing gear rotatablymounted upon said engine and connected in driving relationship with saidcrankshaft, a pair of Weights, each of said Weights being pivotallyconnected at one end to either side of said timing gear, spring meansyielda-bly biasing the free ends of said weights inwardly, a gear sectoron each of said weights, a cam member rotatably mounted adjacent to saidtiming gear, said cam member including a plurality of gear teeth indriving engagement with said gear sectors whereby outward movement ofthe free end of said Weights will cause rotation of said timing cam withrespect to said timing gear, breaker points connected in series withsaid coil and operatively associated with said cam, a lobe on one end ofsaid cam, said timing gear having a depression in the face thereof, saiddepression being positioned in correspondence with the position of saidlobe when the cam is rotated with respect to said timing gear to apredetermined position, a

, r c r 7 starter motor operatively connected to said engine and aswitch means connected to turn off and on said starter motor, resilientmeans yieldably biasing said cam means axially toward said timing gear,a member slidably mounted within said engine between a portion of saidcam and said switch means whereby rotational movement of said camrelative to said timing gear will cause said lobe to engage said recessthereby allowing said timing cam to move axially toward said gear andthe corresponding movement of said member being adapted to actuate saidswitch means to stop sa-id starter motor. 7

3. In an ignition system for an internal combustion engine having arotating crankshaft, the combination comprising; a bi-polar source ofmagnetic energy mounted for rotation in correspondence with saidcrankshaft, the poles of said source of magnetic energy having centerlines of on said core, mounting means for said core and said source ofsaid magnetic flux to provide relative rotational movement between saidcore and said source of flux,

means drivingly connected between said mounting means and the crankshaftof said internal combustion engine, a

' pair of normally closed contacts connected in series with open atrelatively high notational speeds when said two a predetermined angulardisplacement; electric current generating means stationarily mountedwith respect to 7 magnetic poles are positioned substantially oppositethe first and second iegs of said core and to retard said cam atrelatively low rotational speeds to a second position adapted to opensaid breaker points when said poles are positioned adjacent said secondand third legs of said core,

a starter motor mounted in operative relationship to said internalcombustion engine, and circuit means connecting said starter motor whensaid last named means is opercrankshaft; a weight pivotally mounted tartne end upon 1 the rotatable member, the other end of said weight beingadapted to move outwardly when said member is rotated at a predeterminedspeed; a timing cam rotatably mounted with respect to said member andsaid weight being operativelyt connected to'said timing cam to rotatesaid timing cam relative to said member when the free end of said Weightis thrown outwardly by centrifugal force; resilient means operativelyassociated with said weight for yieldably biasing the free end of saidweight inwardly relative to the axis of rotation of said member;normally closed switch means connected in series with said primarywinding and operatively associated with said timing cam, said timing cambeing positioned with the free end of said weight atits inward positionto open said switch means during'the reversal of magnetic energy throughsaid coil and positioned with the free end of said weight at its outwardposition to open said switch means during anin-rush of magnetic energythrough said core member; a starter motor mounted on said engine; andcircuit means interconnecting said starter motor with a source of energytherefor, said circuit means including means forenergizing said startermotor and means responsive to the. movement of said cam member to saidoutward position to deenergize said starter motor. I

4. In an internal combustion engine, a core having three able in oneposition and for allowing energization of said a starter motor whensaid-means is in another position.

5. In combination with an internal combustion engine having a rotatablecrankshaft and a sparking member mounted within a combustion chamber; abi-polar source of magnetic energy mounted for rotation on saidcrankshaft; means responsive to variations in magnitude and direction ofmagnetic energy sta-tionarily mounted on said engine and in energytransferring relationship with said source of magnetic energy, saidmeans including a pair of output terminals and having a three-leggedcore member of magnetizable material; switch means connected to saidpair of terminals; speed responsive means connected to said switch meansfor actuating the same in timed relationship with said crankshaftwhereby said switch means is actuated for a change in flux in said coremember in one direction for a relatively low speed and said switch meansis actuated during a change in flux in another direction for highspeeds; means interconnecting said ouput terminals to said sparkingmembers; a starting motor mounted in operative relationship upon saidinternal combusti-on engine; and circuit means interconnecting saidstarting motor with a source of energy therefor, said circuit meansincluding means for energizing said starting motor and means connectedto said speed responsive means for de-energizing said starting motor inaccordance with the position of said speed responsive means forrelatively high rotational speeds.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING INCOMBINATION; AN ENGINGE INCLUDING A ROTATABLE CRANKSHAFT, A SPARKLINGMEMBER MOUNTED WITHIN A COMBUSTION CHAMBER OF SAID ENGINE, A SOURCE OFMAGNETIC ENERGY MOUNTED FOR ROTATION UPON SAID CRANKSHAFT, ELECTRICCURRENT GENERATING MEANS STATIONARILY MOUNTED ON SAID ENGINE AND INMAGNETIC ENERGY TRANSFERRING RELATIONSHIP WITH SAID SOURCE OF MAGNETICENERGY, SAID GENERATING MEANS INCLUDING A PAIR OF OUTPUT TERMINALS, AFIRST SWITCH MEANS CONNECTED TO SAID OUTPUT TERMINALS, ACTUATOR MEANSRESPONSIVE TO THE VELOCITY OF ROTATION OF SAID CRANKSHAFT FOR OPERATINGSAID FIRST SWITCH MEANS AT RELATIVELY HIGH ROTATIONAL SPEEDS UPON ANIN-RUSH OF MAGNETIC ENERGY TO SAID GENERATING MEANS AND FOR OPERATINGSAID FIRST SWICTCH MEANS AT RELATIVELY LOW RATIONAL SPEEDS UPON THEREVERSAL OF THE DIRECTION OF MAGNETIC ENERGY TRANSFERRED TO SAIDGENERATING MEANS, CONDUCTOR MEANS INTERCONNECTING AT LEAST ONE OF SAIDOUTPUT TERMINALS, AND SAID SPARKING MEMBER, A STARTER MOTOR CONNECTED TOSAID ENGINE, CIRCUIT MEANS INTERCONNECTING SAID STARTER MOTOR AND ASOURCE OF ENERGY THEREFOR, SAID CIRCUIT MEANS INCLUDING MEANS OPERABLETO ENERGIZE SAID STARTER MOTOR AND MEANS CONNECTED TO SAID ACTUATORMEANS OPERABLE TO DE-ENERGIZE SAID STARTER MOTOR AT RELATIVELY HIGHROTATIONAL SPEEDS.